final review monday, may 5th. functional components process manager: creates/removes processes...
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Functional ComponentsFunctional Components
Process Manager: creates/removes Process Manager: creates/removes processesprocesses
Scheduler: allocates processes to Scheduler: allocates processes to processorsprocessors
Memory Manager: allocates pages, Memory Manager: allocates pages, swaps pages, translates addressesswaps pages, translates addresses
File Manager: handles directories and File Manager: handles directories and file accessfile access
Functional ComponentsFunctional Components
Device Manager: maintains drivers Device Manager: maintains drivers and controls accessand controls access
Network Manager: handles Network Manager: handles transmissionstransmissions
I/O ManagerI/O Manager
Process BlockProcess Block
IDID
ProcessorProcessor
Address space pointerAddress space pointer
PriorityPriority
OwnerOwner
StateState
Key ComponentsKey Components
Address SpaceAddress Space
Program CounterProgram Counter
Instruction StackInstruction Stack
ThreadThread– Contains registersContains registers
Process StatesProcess States
CREATE READYSchedule
RunningTerminate Terminated
HALTEDBlocked
Suspended
Interrupt
Activate
Request
Suspend
Retrieve
Release
Timed out
Scheduling AlgorithmsScheduling AlgorithmsNon-preemptiveNon-preemptive– First Come, First ServedFirst Come, First Served– Shortest Thread NextShortest Thread Next– PriorityPriority– DeadlineDeadline
PreemptivePreemptive– Shortest Thread NowShortest Thread Now– Dynamic PriorityDynamic Priority– Round RobinRound Robin
Pages v SegmentsPages v Segments
Pages are constant size, segments Pages are constant size, segments variablevariable
One page per frame, segments could One page per frame, segments could be clusteredbe clustered
Segment virtual address requires Segment virtual address requires lengthlength
Pages have internal fragmentation, Pages have internal fragmentation, segments have externalsegments have external
FragmentationFragmentation
Internal: “holes” in page from Internal: “holes” in page from released variablesreleased variables
External: freed storage smaller than External: freed storage smaller than next allocationnext allocation
Prevention/alleviation:Prevention/alleviation:– Free space listFree space list– ReallocationReallocation– DefragmentationDefragmentation
Replacement SchemesReplacement Schemes
RandomRandom
FIFOFIFO
Least Recently UsedLeast Recently Used
Least Frequently UsedLeast Frequently Used
OptimalOptimal
ClockClock
Data GatheringData Gathering
Direct pollingDirect polling– Check for next inputCheck for next input
DMADMA– Interactive connection between register Interactive connection between register
and sourceand source
Interrupt-DrivenInterrupt-Driven
SemaphoresSemaphores
Binary v countingBinary v counting
Wait() checks if semaphore value is 0Wait() checks if semaphore value is 0– Waits until it isWaits until it is– Once 0, decrementsOnce 0, decrements
Signal() increments valueSignal() increments value
MonitorsMonitors
Function to request entry into Function to request entry into MonitorMonitor
Critical data – accessible only within Critical data – accessible only within monitormonitor
Conditional Variable and Conditional Variable and corresponding queuecorresponding queue
Conditions for DeadlockConditions for Deadlock
Mutual ExclusivityMutual Exclusivity
Hold and WaitHold and Wait
Non-preemptionNon-preemption
Circular WaitCircular Wait
Deadlock PreventionDeadlock Prevention
Total Request ObtainTotal Request Obtain
Single Write LockSingle Write Lock
PreemptionPreemption
Resource OrderingResource Ordering
Network LayersNetwork Layers
PhysicalPhysical
Data LinkData Link
NetworkNetwork
TransportTransport
SessionSession
PresentationPresentation
ApplicationApplication
Data ConcernsData Concerns
AvailabilityAvailability
ConfidentialityConfidentiality
IntergrityIntergrity
AuthenticityAuthenticity
Active AttacksActive Attacks
MasqueradeMasquerade
Keystroke captureKeystroke capture
Message ModificationMessage Modification
Denial of ServiceDenial of Service
Malicious IntrusionsMalicious IntrusionsMasqueraderMasqueraderHackerHackerPassword guessingPassword guessingCommunication tappingCommunication tappingTrap doorTrap doorLogic bombLogic bombTrojan HorseTrojan HorseVirusVirusWormWormZombieZombie
Virus StagesVirus Stages
DormantDormant
PropogationPropogation
TriggeringTriggering
ExecutionExecution
Data ProtectionData Protection
Access tokensAccess tokens
EncryptionEncryption
PermissionPermission
Memory keysMemory keys
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